Polyesters, polyamides, polyimides and polybenzoxazoles have been developed as high-reliability organic polymer materials and have a large market in the field of electronic devices, engineering plastics for automotive and aerospace uses, environmental technologies such as photovoltaic power generation systems and fuel cells, medical materials and optical materials. Various kinds and forms of such polymers, including polyamides typified by Nylon and Kevlar (tradenames), polyarylates used as liquid crystalline polymers, polyimides typified by Kapton (tradename) and polybenzoxazoles typified by Zylon (tradename), are already put into practical use.
Polymerization processes depend on the combination of monomers. In the case of production of the polyester, there can be used a process of polycondensation of a dicarboxylic acid with a diol in the presence of a condensation agent or a process of conversion of a dicarboxylic acid to an acid chloride or ester followed by polycondensation of the acid chloride or ester with a diol. In the case of production of the polyamide, there can be used a process of polycondensation of a dicarboxylic acid with a diamine in the presence of a condensation agent or a process of conversion of a dicarboxylic acid to an acid chloride or ester followed by polycondensation of the acid chloride or ester with a diamine. In the case of production of the polyimide, there can be used a process of polymerization of a diamine with a tetracarboxylic dianhydride followed by dehydration ring closure of the polymerization product. In the case of production of the polybenzoxazole, there can be used a process of polycondensation of a dicarboxylic acid with a bisaminophenol in the presence of a condensation agent or a process of conversion of a dicarboxylic acid to an acid chloride or ester followed by polycondensation of the acid chloride or ester with a bisaminophenol.
Among others, attentions are being given to aromatic polyesters, aromatic polyamides and derivatives thereof in the field of printed circuit boards, semiconductors and displays because of their high reliability and good dimensional stability. On the other hand, there has been a continuing demand for fine patterning to achieve high density packaging and thin film formation in the applications of these aromatic polyester and polyamide materials. The aromatic polyester and polyamide materials are required to attain not only higher reliability such as lower water absorption but also improved electrical characteristics such as lower dielectric constant.
The introduction of a fluorine atom into aromatic polymers leads to improvements in polymer performance, such as hydrophobic and lipophobic properties, low water absorption, corrosion resistance, transparency, photosensitivity, low refractive index and low dielectric constant, without sacrificing high reliability. The fluorinated aromatic polymers have thus been developed and put into practical use in a wide range of material fields, notably advanced material fields. Further, it has been attempted to introduce fluorine into diamine monomers for condensed polymers. There are in practical use fluorinated aromatic polymers derived from aromatic diamine and dihydroxy monomers in each of which a fluorine atom or a trifluoromethyl group substitutes for a hydrogen atom on the aromatic ring and derived from bis(hydroxyamine) monomers each of which has a hexafluoroisopropenyl group as a central atomic group between aromatic hydroxyamines.
Patent Document 1 discloses a fluorinated aromatic polyamide that combines visible light transparency with dimensional stability by the introduction of a trifluoromethyl group directly to an aromatic ring of the rigid polyamide framework. By the effect of such fluorine introduction, the polymerization reaction can proceed even in an organic solvent although it has typically been necessary to carry out the polymerization reaction in sulfuric acid. The application of the fluorinated aromatic polyamide is however limited as the framework of the aromatic polyamide is so rigid that the polyamide needs to be heated at a high temperature of 280° C. or higher to form a flexible film thereof.
Patent Document 2 discloses a rigid, fully aromatic polyester that combines light transparency in the 850 nm band range with high thermal resistance by the substitution of all of hydrogen atoms with a fluorine atom or a trifluoromethyl group. As the framework of the aromatic polyester is rigid, the polymerization temperature needs to be 300° C. or higher to increase the polymerization degree of the polyester.
Non-Patent Document 1 discloses a dicarboxylic acid monomer in which carboxyl groups are bonded to the ortho positions of a fully fluorinated benzene ring via fluorinated methylene groups, but makes no mention about the production of a polymer from the dicarboxylic acid monomer. Further, Non-Patent Document 2 discloses bis(2-ethoxycarbonyl-1,1,2,2-tetrafluoroethyl)benzene but also does not make any mention about the production of a polymer therefrom.